North Sea 40-km pipeline decontaminated and cleared for gas production
North Sea, Offshore
As the gas was diverted to the production platform, ~1,000 bbl of condensate were collected and stored, and ~3,000 bbl of water were treated and disposed in compliance with environmental regulations. The water treatment and disposal solution saved shipping and disposal costs, as well as platform deck space.
An operator in the North Sea was facing challenges with a subsea pipeline connected to an offshore well. To increase gas flow in the well, the production zone would be isolated and a new completion run. Once a new layer was perforated and hydraulic fracturing applied, the operator expected substantial gas production to commence. However, during previous operations, the 40-km undersea pipeline had accumulated a mixture of water and condensate that threatened to limit gas production.
The operator trusted SLB to quickly respond to the challenge and provide an appropriate solution to prepare the well for production. To empty the contents of the pipeline, a series of pigs would be deployed to inspect the line and push out the hydrocarbon mixture. Filtered seawater would first be used and later displaced by nitrogen to flush out the pipeline. All the return fluids from the pipeline would be collected and reliably handled at the offshore platform.
SLB deployed a Production ExPRESS™ rapid production response solutions package to handle the decontamination process. The solution included a choke to control the flow, separator to remove water from the condensate, and tanks for condensate storage. A ClearPhase™ mobile testing discharge treatment unit was included to separate the residual oil particles from the water to comply with environmental regulations for an oil limit of 30 ppm to be dumped overboard.
The entire package was configured efficiently to make good use of the limited deck space and formed an integral part of the operation to enable ecologically sound disposal of the contaminants. Close monitoring of the flow was critical to stay within the operating pressure limits of the subsea tree hoses.
Decontamination equipment included a separator, such as this one, to remove water from the condensate, and tanks for condensate storage.
The Production ExPRESS solutions package successfully removed condensate and water residuals from the pipeline. While gas was being diverted to the production platform, ~1,000 bbl of condensate were collected and stored, and ~3,000 bbl of water were treated and disposed in compliance with environmental regulations. By enabling onsite water treatment and disposal, the Production ExPRESS solutions package saved the operator shipping and disposal costs while eliminating the need for multiple large storage tanks on the limited platform deck space.